Lubricating oil composition



United Stat att O M 2,996,452 LUBRICATING OIL, COMPOSITION Louise F. Peale, Philadelphia, and Joseph F. Messina,

Havertown, Pa., assignors to the United States of America as represented by the Secretary of the Army No Drawing. Filed Mar. 30, 1960, Ser. No. 18,777 2 Claims.- (Cl. 25249.8) (Granted under Title 35, US. Code (1952), sec. 266) The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment to us of any royalty thereon.

This invention relates toimproved lubricants containing as a major lubricating component oil of mineral origin. In particular, the invention relates to lubricating compositions of this type having improved extreme pressure and anti-wear characteristics.

A particular property required by many mineral base lubricants used today is an ability to prevent seizure and scoring of relatively moving metallic surfaces operating under extremely high pressures per unit area, in many cases considerably in excess of 10,000 psi. Pressures on this order have long been encountered in the machine industry. Also, recent automobile design has involved the use of smaller gears of the worm and hypoid type which operate under extremely high pressure loads. Consequently, for effective lubrication, lubricants capable f withstanding pressures appreciably higher than those at which ordinary mineral base oil lubricant films will rupture have been required.

-It is therefore a principal object of the invention to provide a compounded lubricating product of mineral base oil possessing extreme pressure and anti-wear characteristics of a high order such as those encountered in hypoid gear oils.

It is another object of the invention to provide a lubricant having improved extreme pressure and anti-wearproperties, said lubricant comprising a major proportion of an oil of mineral :origin having a long chain phosphorus derivative of a fatty acid blended therewith.

Other objects and features of the invention will become apparent as the invention is more fully hereinafter disclosed.

In accordance with these objects it has been discovered that minor additions of selected long chain phosphorus derivatives of fatty acids to mineral base oils are characterized by good extreme pressure and anti-wear properties. More specifically, it has been found that di(2-ethylhexyl) lauroxyethylphosphonate and diethyl oleoxyethyl phosphate are capable of imparting these desirable properties to mineral base oils.

Mineral oil SAE 40 only is presented in the table following. It is to be understood however that the invention is not to be considered as being limited to this specific viscosity as it will be apparent to those skilled in the art that a wide variety of visoosities of mineral oils may be employed in formulating the lubricant contemplated herein.

The lubricity agents of the present invention are made by conventional methods and will not be described. 1 through 6 Weight percentages of each of di(2-ethylhexyl) lauroxyethylphosphonate,

2,996,452 Patented "Aug. 15, 1961 Ice was intimately blended with varying SAE mineral loils-and then subjected to extreme pressure and anti-wear evaluation tests. These tests were conducted on conventional laboratory equipment and will not be described, their operations being well known to those skilled in the art. For example, anti-wear data were obtained on 'the Shell 4- ball wear tester while extreme pressure data were determined using the well-known Falex andShe1l4-ball'extreme pressure tester. Description of the Shell 4-ba1l testers may be found in an article by G. D. Boerlage, Engineering, vol. 136 (1933), p. 46 et seq. The Falex extreme pressure tester is described in Lubrication Engineering, September 1946, V. A. Ryan.

The tabulated comparative data following illustrates the extreme pressure and anti-wear effectiveness of the present invention when incorporated in a mineral base oil such as SAE 40:

Falex Shell-4-Ball Ex- Shell- Extreme Pressure Wt. A-Ball treme Per- Wear Pres- Additive cent Scar sure Addi- Di- Jaw Seizure Weld tive ameter Load at Load Load (mm.) Failure (Kg) (Kg) (lbs.)

None 734 600 50 140 Di(2 ethylhexyl) lauroxyethyl phosphonate 2 563 1, 750 100 180 Do 5 550 1, 750 90 180 Diethyl olexyethyl phosphate- 2 .609 1, 750 180 5 .685 l, 500 80 180 2 556 600 60 140 Do 5 504 600 60 140 SAE Hypoid gear oil (Commercial) 525 1, 750

11 Seizure may be defined as the load at which a significant [increase in wear scar diameter takes place.

b Weld may be defined as the load at which the balls fuse rtogethel.

Commercial tric-resyl phosphate imparts excellent antiwear properties to the mineral oil but is of no benefit in improving its extreme pressure characteristics.

In addition to the property of being able to withstand extreme pressure loads and wear there are other factors which must be considered in evaluating a lubricant. Among the most important is the tendency of the lubricant to corrode the containers in which it is stored and the bearings, gears and housings with which it comes in contact during use. The above tabulated data show the di(2-ethylhexyl) lauroxyethylphosphonate and diethyl oleoxyethyl phosphate to compare satisfactorily with the commercial hypoid gear oil in extreme pressure characteristics, and only slightly inferior in anti-wear properties. However, commercial hypoid gear oil normally contains a minimum of approximately 15% of phosphorus, chlorine and sulfur type additives, the latter two being the most corrosive. It should be apparent therefore that the small quantities of phosphorus contained within the lubricity agents of the present invention, and the absence of any chlorine or sulfur additives, will not tend to corrode the metals as greatly as the commercial hypoid gear oil.

All values presented in the table are averages of five different measurements. Maximum variance among the five values was confined to within a 10% range. Although 2 and 5 weight percentages of the lubricity additives of the invention are presented only, it should be understood that intermediate additions were found equally satisfactory, that is, between 2 and 5 weight percentages.

From the data ,hreinaboveiset forth, it will become evident that the lubricity additives of the present invention, when confined within the prescribed range, improves both extreme pressure and anti-wear characteristics of the mineral base oil. Further, its corrosive tendencies are considerably lower than the presently used commercial hypoid gear oil. Amounts of the respective lubricity additives below about 2 weight percent do not produce sufiicient advantageous effects to render the composite oil lubricant adequate for extreme pressure and anti-wear use. Similarly, if the' additive is incorporated with the mineral oil in quantities greater than about 5 weight percent, the composite lubricant shows no further improvement in the level of these properties and, in several instances, a slight decrease in levels results. I V

. We claim: 7

,7 1. A lubricant composition having good extreme pressure, anti-wear and anti-corrosive properties suitable for 4 p ,y I E W use in hypoid gear systems, said lubricant composition consisting essentially of 2 to 5 weight percent of di(2* ethylhexyl) lauroxyethylphosphonate and the balance be ing an oil of mineral origin.

2. A lubricant composition having good extreme pressure, anti-wear and anti-corrosive properties suitable for use in hypoid gear systems, said lubricant composition consisting essentially of about 2 to 5 weight percent-of diethyl ole'oxyethyl phosphate and the balance being an 10 oil of mineral origin. 4

References Cited in the file of this patent UNITED STATES PATENTS 2,285,853 Downing a a1. June 9, 1942 2,478,441 Wiley Aug. 9, 1949 FOREIGN PATENTS 560,741 Canada July 22, 19s 

1. A LUBRICANT COMPOSITION HAVING GOOD EXTREME PRESSURE, ANTI-WEAR AND ANTI-CORROSIVE PROPERTIES SUITABLE FOR USE IN HYPOID GEAR SYSTEMS, SAID LUBRICANT COMPOSITION CONSISTING ESSENTIALLY OF 2 TO 5 WEIGHT PERCENT OF DI(2ETHYLHEXYL) LAUROXYETHYLPHOSPHONATE AND THE BALANCE BEING AN OIL OF MINERAL ORIGIN. 